INVERTER MOTOR (YASKAWA GA700) VIBRATE WHILE DECELERATION

[Amir177]

Hi everyone, i got some problem with inverter motor. Now I'm using inverter Yaskawa GA700. But right now, I got some problem with that motor. The motor will vibrate when deceleration process. For acceleration, it also got some vibrate but i have countered that problem with change setting at C4-21 (Voltage compensation adjust) = 0. But that change not counter problem while deceleration process. I also have check with mechanical member if any problem with mechanical part, but they said all are fine.

The speed of motor is 25~50. And the vibrated only happened while it decelerate from 50~30, and the rest is smooth.

So anyone can help me to find solution of this problem? I'm really appreciate if you can help me. thank you.

 

[St_Isakovic]

What type of load the motor is running? Can you decouple motor from load and let it run idle so you see if vibration is mechanical in nature.
VFD has an option to skip certain frequencies is you are encountering a mechanical resonance.

Some more information would help, like motor power, application, did it behave like this from the start or just started to happen.

 

[waross]

but they said all are fine.

If I had a dollar for every time they said that and they where wrong.

 

[panter]

If I had a dollar for every time they said that and they where wrong.

...I would be a millionaire. Recently, colleagues reported an electrical problem with 1,1 MW DC motor due to large vibrations, so we spent a lot of time checking motor and old analog DC regulator. Finaly then we asked them to turn off DC switch at rotor and excitation winding two seconds later during test of motor and it showed that the vibrations dropped as well as the rotation speed , it was clear to everyone that they were looking for the problem in the machine assembly. Opening and visual inspection in 10 minutes job revealed chaos in the gearbox .
If you have the opportunity to turn off inverter and do this simple test , you may be able to eliminate any doubts about inverter and motor.

 

[Gr8blu]

Hmm. OP indicates some vibration during acceleration, but more during deceleration. Is the interval the same - or does deceleration take a lot longer (i.e. a coast-down approach)? Might be as simple as sitting on (or at least near) the system resonant frequency longer during the deceleration period. And having that resonance amplified because of harmonics present in the inverter output.